Portable circular saws are very useful, but are limited in the depth they can saw. Chain saw bars and saw chains have been substituted for the circular blade in a circular saw as disclosed in U.S. Pat. No. 4,033,035, but it would be desirable to guard both the nose and the rear side of the chain. West German Pat. No. 804,863 shows a chain saw with a guard along one edge but with no guard over the nose portion of the saw bar. U.S. Pat. No. 1,861,162 discloses a chain saw with a rear guard and a nose guard but with the nose guard preventing boring operations. U.S. Pat. Nos. 2,998,997 and 2,291,470 show nose guards that prevent boring. U.S. Pat. No. 2,638,944 discloses a telescopic annular guard covering a saw bar entirely and permitting boring but normally preventing side cutting.